Method of finishing a displacement chamber in a rotary fluid device

ABSTRACT

A method of finishing a displacement chamber in a rotary fluid device such as a rotary-disk meter, displacement pump and so on which carries a pair of rotors such as rotary disks, revolving gears. The displacement chamber comprises upright semicircular or semicylindrical wall sections and an oval-shaped bottom wall surface. These sections and surface are finished in a single cutting operation, utilizing a single finishing tool having at least two groups of bits provided on its driving shaft with a specific distance therebetween.

United States Patent Mnsakatu Nishioka inventor Tokyo, Japan Appl. No. 849,815

Filed Aug. 13, 1969 Patented Oct. 19,1971

Assignee Oval Kiki Kogyo Kabushiki Kaisha Tokyo, Japan Priority Aug. 17, 1968 Japan 43/58295 METHOD OF FINISHING A DISPLACEMENT CHAMBER IN A ROTARY FLUID DEVICE 4 Claims, 3 Drawing Figs.

US. Cl 408/1, 408/21 Int. Cl B23b 35/00 Field of Search 77/1, 33 C,

4,4C,58,58 Q58 A; 90/14, 15, 15.1

References Cited UNITED STATES PATENTS 2,364,305 12/1944 Martin 77/58 C 2,870,658 l/l959 Melling 77/3 3,289,501 12/1966 Dubrovin 77/61 FOREIGN PATENTS 825,940 12/1951 Germany 77/3 Primary Examiner-Leonidas Vlachos Attorney-Michael S. Striker ABSTRACT: A method of finishing a displacement chamber in a rotary fluid device such as a rotary-disk meter, displacement pump and so on which carries a pair of rotors such as rotary disks, revolving gears. The displacement chamber comprises upright semicircular or semicylindrical wall sections and an oval-shaped bottom wall surface. These sections and surface are finished in a single cutting operation, utilizing a single finishing tool having at least two groups of bits provided on its driving shaft with a specific distance therebetween.

V PATENTEDDEIISIHII 3.614.249.

I summer 2 INVENTOR 0454 EA Tu msm x4 METHOD OF FINISHING A DISPLACEMENT CHAMBER IN A ROTARY FLUID DEVICE The present invention relates to a method of finishing a displacement chamber in a rotary fluid device such as a rotarydisk meter and displacement pump. More particularly, it relates to a method of finishing inner surfaces of the displacement chamber carrying a pair of rotors such as rotary disks, revolving gears and the like which are rotatably engaged or in mesh with each other.

In nearly all of fluid devices of this kind, the displacement chamber comprises an upright wall enclosure extending vertically from the circumferential edge of a plane bottom wall surface and having semicircular wall sections each provided with an inside diameter corresponding to the outside diameter of the rotors. In a conventional method for finishing such displacement chamber, its upright wall enclosure and plane bottom wall surface have to be independently lathed or bored for finishing from a die-cast block of a casing having an inner and outer contour nearly same to a finished one. Because, the conventional method comprising such two steps of finishing process is inevitably accompanied by a number of disadvantages such as follows.

1. A substantially elliptical part which differs at its level from the other remaining parts is produced on the plane bottom wall surface where each cutting or boring operation for finishing the semicircular wall sections falls on, with the result that it is necessary to finish the bottom wall surface by machining again after the cutting or boring operation of said semicircular wall sections has been done.

2. Since said elliptical part is comparatively small and enclosed by the upright wall enclosure having finished surfaces, a tool for cutting and finishing said part should be slender.

And such slender tool can not stand a heavy cutting or boring an inside diameter corresponding to the outside diameter of rotors rotatably mounted inside the chamber and a bottom wall surface which cojointly define the inner surfaces of the displacement chamber are finished by a single step.

More in detail, the present invention method of finishing the inner surfaces of a displacement chamber which carries a pair of rotors of the same diameter is achieved by using a finishing tool comprising a driving shaft having a fastening means at its free end, one or more first bit removably fitted through the fastening means to the driving shaft and provided with a cutting edge extending in parallel with the axial direction of the driving shaft with a distance from the central axis of the driving shaft corresponding to the semidiameter of the rotors and another cutting edge extending horizontally to said axial direction andone or more second bit removably fitted through the fastening 'means to the driving shaft with a specific distance from the central axis of the driving shaft which is shorter compared to the distance between the first bit and the central axis of the driving shaft and provided with a cutting edge having a top end laying on a same level with the secondmentioned horizontal cutting edge of the first bit, said firstmentioned vertical and second-mentioned cutting edges of the first bit operating to finish upright wall enclosure parts of the chamber and their corresponding bottom wall surface parts and the second bit operating to finish, simultaneously with the finishing operation of the first bit, the remaining bottom wall surface parts which are not to be finished by the first bit.

Further in detail, the present invention method of finishing the inner upright and bottom wall parts of a displacement chamber which define together a room for the rotary movement of a pair of rotors of the same diameter is attainable by using the finishing tool of the above-described constructions in this manner that it is driven and vertically advanced towards the bottom wall surface until the bits reach the desired depth by keeping its central axis in alignment with the vertical axis of one of the rotors to be mounted in the chamber, advanced horizontally, while continuously being driven and kept on the same level, towards the vertical axis of another rotor to be mounted in the chamber either by moving the tool itself in relation to the chamber or moving the latter in relation to the former, and retracted in a vertical direction from the bottom wall surface when the central axis of the driving shaft comes in alignment with the vertical axis of said another rotor.

In the accompanying drawing which illustrates a preferred embodiment of the present invention;

FIG. 1 is a perspective view of a rotary fluid device with a displacement chamber which is to be finished in accordance with the present invention method,

FIG. 2 is a view showing said displacement chamber in section with a finishing tool which embodies the present invention method, and illustrating the mode of operation said tool within the chamber, and

P16. 3 is a plan view of said displacement chamber, wherein the working construction of the present invention method is illustrated.

In the rotary-disk flow meter illustrated in the drawing as an example of a rotary fluid device of this kind, a displacement chamber 4 is provided in a block of a casing 5. Said displacement chamber comprises an upright wall enclosure 0 consisting of semicircular wall sections 2, 2 respectively of a diameter substantially equal to that of rotors to be mounted in the chamber and tangential wall sections 3, 3 connecting said two semicircular wall sections, an oval-shaped bottom wall surface b horizontally extending from the inner circumferential edge of said upright wall enclosure a to finish the chamber and a pair of bearing holes 1, 1 provided in the wall surface b with a distance P therebetween. The bearing holes l, l are destined to carry one of the rotary axis of rotors each having a semidiameter R. An inlet and outlet openings 6 and 7 are provided to the displacement chamber 4. The unfinished block of easing 5 with the inlet and outlet openings 6 and 7, bearing holes 11, l and unfinished displacement chamber 4 is obtained by diecasting. Said displacement chamber 4 has an upper opening 8 and the unfinished inner walls, viz, the upright wall enclosure 0 and oval-shaped bottom wall surface b contours of which correspond substantially with or are slightly smaller than those of the finished contours.

ln finishing the inner walls of the displacement chamber, a finishing tool 9 is brought inside the chamber through the upper opening 8 and operated therein. The tool comprises a driving shaft having a fastening means 13 at its free end and a bit 10 removably fitted through said fastening means to the driving shaft and provided with a cutting edge 10:: extending in parallel with the axis of the driving shaft at a distance R from the central axis of the driving shaft and another cutting edge 10b extending horizontally to said axis. Firstly, the tool is brought at its vertical central axis in alignment with the axis of one of the bearing holes 1, ll, driven at a high velocity and advanced towards the bottom wall surface b, whereby the cutting edge 10a comes into contact with one of the semicircular wall sections 2, 2 and cuts and finishes the inner surface of said section. When said cutting edge reaches a desired depth, either the tool or casing 5 is moved while the former is continuously driven so that the tool shifts its location towards another bearing hole, whereby the cutting edge l llb cuts and finishes the oval-shaped bottom wall surface b to a desired level. Shortly after the central axis of the tool 9 comes in alignment with said another bearing hole, it is retracted vertically from the bottom wall surface towards the upper opening whereby the cutting edge 10a comes into contact with the another wall section and cuts and finishes the inner surface of said section to a desired diameter. Since the cutting edge 10b can cut and finish only parts of the oval-shaped bottom surface b but leaves a substantially lenticular-shaped portion of the bottom surface ll unfinished, which is located about the middle part of the line connecting the bearing holes 1, l, the tool is additionally provided with another bit l2 which is removably fitted by the fastening device 13 to the driving shaft with a specific distance r therefrom. The bit 12 cuts and finishes, simultaneously with the cutting and finishing operation of the bit 10, the remaining parts of the bottom wall surface which are not subjected to the cutting operation of the bit 10.

From the construction shown in FIG. 3, it shall be known that the above-mentioned specific distance r is obtainable from the following expression:

R m 2 r g n wherein n represents a half of major axisof the elliptical part 11, m a half of minor axis of said elliptical part, R a distance between the central axis of the cutting device 9 and the bit 10 and r a distance between the central axis of the device 9 and the another bit 12.

Unless the distance r of the bit 12 from the axis of the cutting device 9 satisfies the above expression, the elliptical part 11 remains unfinished.

In the embodiment illustrated by the accompanying drawing and described in the above in conjunction with the drawing, the bits 10 and 12 provided to the finishing tool 9 are respectively single but they may be in groups as far as they satisfy the above expression.

In the present invention method, as readily known from the above description, it is possible to finish, through a single process, both upright semicircular wall sections and an ovalshaped bottom wall surface of a displacement chamber by vertically advancing, horizontally shifting and vertically retracting a single finishing tool provided at its outer most circumferential edge with at least a bit and further with at least one other bit at the location apart from the vertical control axis of the driving shaft of the tool at a distance larger than or equal to a half of the major axis of an elliptically shaped part of the bottom wall surface which are not to be subjected to the firstmentioned bit and equal to or smaller than the distance between the vertical central axis of the driving shaft and said first-mentioned bit reduced by a half of the minor axis of said elliptically shaped part.

Thus, the present invention method is characterized in that it can finish thoroughly all the inner surface of a displacement chamber which are required to be finished, in a single cutting operation with a single finishing tool and without producing any unfinished part or bottom wall parts which are different on their levels, viz, those, such as seen in a displacement chamber finished in accordance with a conventional method in which the inner surfaces are cut independently about two axes of a pair of rotors to be mounted in the chamber, and further that since a heavy dutied and big armed driving shaft and bits are utilizable in the present method, a fine and rapid finishing operation can easily be made without any particular skill on a various kind of materials including those hard for cutting such as a stainless steel. In the present method, vibration or pulsing in a cutting operation which accompanies with the use of a slender driving shaft or bit is also eliminated.

What is claimed is: 1. A method of finishing the inner surfaces of a displacement chamber open at one end of a rotary gear pump or similar rotary fluid displacement device for mounting a pair of interengaging rotors having equal diameters therein, in which said inner surfaces include a pair of semicylindrical laterally displaced upright surface portions having each a diameter substantially equal to that of said rotors and a substantially ovalshaped bottom wall surface normal to said upright surface portions, said method comprising the steps of advancing through said open end of said chamber a rotating finishing tool with its axis of rotation aligned with the axis of one of said semicylindrical surface portions and having at least one bit having a cutting edge parallel to said axis of rotation and spaced therefrom a distance equal to the radius of said semicylindrical surface portion and at its lower end at least one cutting point aligned with said cutting edge to thus finish said one semicylindrical surface portion; moving, after said cutting point has reached said bottom wall surface, said chamber and said rotating finishing tool transversely relative to each other so that the axis or rotation moves along a plane including the axes of said upri ht semicylindrical surface portrons until the axis of said rota lng tool IS aligned with the axis of the other of said pair of semicylindrical surface portions to thereby finish part of said bottom wall surface with said cutting point of said one bit; simultaneously subjecting said bottom wall surface to the finishing action of another cutting point provided on said finishing tool in a common plane normal to said axis of rotation with said cutting point of said one bit and arranged spaced from said axis of rotation such a distance that said other cutting point finishes during said transverse movement that part of said bottom wall surface which is not finished by said cutting point of-said one bit; and retracting said rotating finishing tool along the axis of said other of said semicylindrical surface portions so as to finish said other semicylindrical surface portion.

2. A method as defined in claim 1, wherein continuations of said semicylindrical surface portions intersect each other and said bottom wall surface to define on said bottom wall surface an area of lenticular outline having a large axis and a small axis, which area is not finished by said cutting point of said one bit during said transverse movement of said rotating finishing tool, and wherein said other cutting point is spaced from the axis of rotation of said finishing tool a distance which is smaller than said large axis but greater than said small axis.

3. A method as defined in claim 1, wherein said transverse movement of said finishing tool and said chamber relative to each other is performed by moving said chamber relative to said tool while maintaining the axis of said tool in place.

4. A method as defined in claim 1, wherein said transverse movement of said finishing tool and said chamber relative to each other is performed by moving said tool relative to said chamber while maintaining said chamber stationarily. 

1. A method of finishing the inner surfaces of a displacement chamber open at one end of a rotary gear pump or similar rotary fluid displacement device for mounting a pair of interengaging rotors having equal diameters therein, in which said inner surfaces include a pair of semicylindrical laterally displaced upright surface portions having each a diameter substantially equal to that of said rotors and a substantially oval-shaped bottom wall surface normal to said upright surface portions, said method comprising the steps of advancing through said open end of said chamber a rotating finishing tool with its axis of rotation aligned with the axis of one of said semicylindrical surface portions and having at least one bit having a cutting edge parallel to said axis of rotation and spaced therefrom a distance equal to the radius of said semicylindrical surface portion and at its lower end at least one cutting point aligned with said cutting edge to thus finish said one semicylindrical surface portion; moving, after said cutting point has reached said bottom wall surface, said chamber and said rotating finishing tool transversely relative to each other so that the axis or rotation moves along a plane including the axes of said upright semicylindrical surface portions until the axis of said rotating tool is aligned with the axis of the other of said pair of semicylindrical surface portions to thereby finish part of said bottom wall surface with said cutting point of said one bit; simultaneously subjecting said bottom wall surface to the finishing action of another cutting point provided on said finishing tool in a common plane normal to said axis of rotation with said cutting point of said one bit and arranged spaced from said axis of rotation such a distance that said other cutting point finishes during said transverse movement that part of said bottom wall surface which is not finished by said cutting point of said one bit; and retracting said rotating finishing tool along the axis of said other of said semicylindrical surface portions so as to finish said other semicylindrical surface portion.
 2. A method as defined in claim 1, wherein continuations of said semicylindrical surface portions intersect each other and said bottom wall surface to define on said bottom wall surface an area of lenticular outline having a large axis and a small axis, which area is not finished by said cutting point of said one bit during said transverse movement of said rotating finishing tool, and wherein said other cutting point is spaced from the axis of rotation of said finishing tool a distance which is smaller than said large axis but greater than said small axis.
 3. A method as defined in claim 1, wherein said transverse movement of said finishing tool and said chamber relative to each other is performed by moving said chamber relative to said tool while maintaining the axis of said tool in place.
 4. A method as defined in claim 1, wherein said transverse movement of said finishing tool and said chamber relative to each other is performed by moving said tool relative to said chamber while maintaining said chamber stationarily. 